1. Field of the Disclosure
The present disclosure relates in general to patient monitoring and in particular to oximeter patient monitors capable of monitoring one or more physiological parameters including a pulse rate from a noninvasive optical sensor.
2. Description of the Related Art
A desirable feature of patient monitors, including oximeters such as oximeters, co-oximeters, and the like, includes at least one of an audio and video indication of a pulse occurrence substantially corresponding to a patient's pulse. Such indications of a pulse occurrence may be caused by a trigger output used to initiate an audible tone “beep” or a visual pulse indication on a display.
In some systems, when signal(s) from a noninvasive optical sensor include sufficient distortion, high noise, or simply present low signal quality, pulse indications may be difficult to calculate. In some systems, the oximeter may simply determine that no pulse indication is presented to a caregiver.
In other systems, the oximeter may attempt to determine pulse occurrences during distortion, high noise, motion-induced noise, or during low signal quality or confidence. For example, in U.S. Pat. No. 6,606,511, which is assigned to Masimo Corporation (“Masimo”) of Irvine, Calif., which is the assignee of the current application and incorporated by reference herein, a pulse trigger output from a rule-based processor is responsive to pulse waveforms of the patient's oximeter-derived photo-plethysmograph waveform in low-noise or no-distortion situations. However, during high-noise or distortion situations, the pulse trigger output may advantageously become dependent on an average or other statistical determination of the pulse rate. This “intelligent beep” reliably indicates the patient's pulse, yet responds to patient arrhythmias, asystole conditions and similar irregular plethysmographs. An example of the determination of pulse rate in the presence of distortion is described in U.S. Pat. No. 6,002,952, No. 6,463,311, No. 6,684,090, all of which are assigned to Masimo Corporation of Irvine, Calif., and incorporated by reference herein.
As disclosed in the '511 patent, when there is relatively no distortion corrupting a plethysmograph signal, the processor may analyze the shape of the pulses in the waveform to determine where in the waveform to generate the pulse indication. When distortion is present, looser waveform criteria can be used to determine if pulses are present. For example, when pulses are present, the pulse indication is based upon an averaged pulse rate. If no pulses are present, no indication occurs.
In the disclosed embodiment, the pulse indicator provides a trigger and amplitude output. The trigger output is used to initiate an audible tone “beep” or a visual pulse indication on a display, such as a vertical spike on a horizontal trace, a rising pulsing or constant bar display, one or more specific colors of a displayed parameter or trace, one or more LEDs or other visual elements, combinations of the same, or the like. The amplitude output is used to indicate data integrity and corresponding confidence in the computed values of saturation and pulse rate. The amplitude output can vary a characteristic of the pulse indicator, such as beep volume or frequency or the height of the visual display spike.